Former New York Mayor Rudy Giuliani visits Cedar Rapids, Iowa, originally uploaded by millhollin.

The big three Republican presidential candidates have released their fundraising numbers and Rudy Giuliani is standing alone at the top. Although it’s still early, I suspect that only Fred Thompson might be able to keep pace with Giuliani. (We probably won’t be able to fully judge Thompson’s fundraising ability until the end of September.)

It’s not just Giulani’s money total that’s impressive — he raised $15 million for the primary and $2 million for the general election in the second quarter. The fact that Giuliani’s campaign ended the quarter with zero debt and $18 left in the bank is what stands out in stark contrast to the other campaigns.

I’m still floored by John McCain’s free-spending ways, which left him with just $2 million cash-on-hand. But I was even more surprised to learn that Mitt Romney had blown through $32 million in just six months, leaving him with $12 million in the bank. The only reason pundits aren’t writing Romney’s political obituary today (as was the case with McCain yesterday) is that Romney can continue loaning himself money.

The next round of numbers to watch will be what the Republicans raised online vs. their Democrat counterparts. As I wrote after the first-quarter deadline, it wasn’t even close.

UPDATE — 5:03 p.m.: When citing the Giuliani numbers, I should have noted that because he’s raising money for both the primary and general election, about $15 million cash-on-hand is for the primary. The other $3 million is for the general election. In contrast, Romney’s $12 million is for the primary.